Generally, cancer tissues which occur in body organs, for example, organs such as a liver are treated by a non-surgical method or a surgical operation.
In this case, the surgical operation mainly resects a body with a lesion, and as a result, the lesion becomes very wide. Therefore, the surgical operation has a problem in that a big scar remains, convalescence is required for a considerable period of time, and the like. Further, cancer tissues, and the like are likely to recur in body organs and in the case of the recurrence, a re-operation needs to perform, and therefore, the surgical operation has a problem in that pain, financial burden, and risk of a patient are increased.
As a result, the non-surgical methods, for example, transarterial chemoembolization, percutaneous ethanol injection therapy, generalized chemotheraphy, local heat therapy, and the like have been used. Among those, the local heat therapy has been known as the most effective in improving a short-term treatment outcome or a long-term survival rate.
An example of the local heat treatment may include high-frequency heat treatment, microwave cauterization, laser cauterization, and the like. Among those, the high-frequency heat treatment has been used most effectively.
Here, when the cancer tissues occur in the body organs, for example, a liver, the high-frequency heat treatment is a treatment method for cauterizing and necrotizing only the cancer tissues with high-frequency heat without performing a resection on only the cancer tissues.
To this end, an electrode apparatus for the typical high-frequency heat treatment is configured in a structure in which a ground pad as a passive electrode body generally adheres to a patient's epidermis, a needle-shaped electrode as an active electrode body is inserted into a lesion, and then the ground pad and the needle-shaped electrode are electrically connected to a high-frequency generator.
Therefore, when power is applied to the high-frequency generator, a current transfer path from an electrode to the ground pad is formed and during the transfer process, friction energy due to vibration of ions increases a temperature of tissues to induce coagulation and necrosis of tissues around a lesion.
However, since the general electrode apparatus as described above performs an operation using a monopolar needle-shaped electrode, the electrode apparatus has a problem in that a high-frequency current flowing through the ground pad attached to the patient's epidermis is not locally applied only to lesions and is applied to the whole path reaching the electrode, and therefore affects normal organs or tissues or burns the portion to which the ground pad is attached.
To solve the problem, as illustrated in FIG. 1, a needle-shaped bipolar electrode 101 which includes an active electrode body 113 disposed at a tip portion of one body 111 and a passive electrode body 115 is proposed.
As illustrated in FIG. 1, the bipolar electrode 101 has a structure in which the active electrode body 113 which disposed at a tip portion of the body 111 is connected to an active terminal 151 of a high frequency generator, the passive electrode body 115 which is disposed at a back portion of the body 111 is connected to a passive terminal 152, and an insulator part 123 is disposed between the active electrode body 113 and the passive electrode body 115, thereby radiating high frequency energy between the active electrode body 113 and the passive electrode body 115. Therefore, a path from the active electrode body 113 to the passive electrode 115 becomes very short, and as a result, a range of a body portion affected by a high frequency current may be remarkably reduced.
However, the typical bipolar electrode 101 generates heat generation due to high-frequency energy radiation around the insulating part 123 as represented by D in FIG. 1, such that the heat generation is extended in an oval shape around the insulating part 123 as represented by F in FIG. 2.
Therefore, when the typical bipolar electrode 101 intends to perform an operation on, in particular, a tubular tissue such as a blood vessel, the typical bipolar electrode 101 has a problem in that since the heat generation range is formed in an oval shape around the insulating part 123 but a lesion to be treated occur in a cylindrical shape along a form of the tubular tissue, the bipolar electrode 101 cauterizes and damages normal tissues around the tubular tissue at a portion (represented by F in FIG. 2) where the heat generation range around the insulating part 123 which is an intermediate point of the heat generation range in a length direction is beyond a lesion, while since the heat generation range does not reach the lesion at both end points of the heat generation range in a length direction, the bipolar electrode 101 does not cauterize the lesion and thus does not perform an effective operation.